Optical disc recording and reproduction apparatus having automatic gate signal generation modes

ABSTRACT

An optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the synchronous clock signal and the signal output from the address detecting means; and gate signal generation switching means for generating gate a signal which controls the analog processing means, based on one of the sector count value held in the sector counter and information obtained from the analog processing means, according to the signal indicating that the address has been detected, which is output from the address detecting means.

This application is a continuation of U.S. application Ser. No.10/218,409, filed Aug. 15, 2002, now U.S. Pat. No. 6,643,235, which is adivisional of U.S. application Ser. No. 09/206,953, filed Dec. 8, 1998,now U.S. Pat. No. 6,459,667.

FIELD OF THE INVENTION

The present invention relates to an optical disc recording andreproducing apparatus and, more particularly to an optical discrecording and reproducing apparatus which uses an optical disc of alarge capacity which requires high precision in control of recording andreproduction, as a recording medium.

BACKGROUND OF THE INVENTION

The optical disc is a general term of disc-shaped recording media suchas a compact disc, a video disc, a phase-change optical disc, a DVD(digital video disc), and the like, which reflect laser beams onrecording surfaces thereof, and read recorded signals by the use ofreflected beams.

There are read-only and recordable optical discs. The recordable opticaldisc includes a WORM(Write Once, Read Many) disc and a rewritable disc.CD-ROMs (Compact Disc Read-Only Memories) are typical of the read-onlydisc. Manufacturers record data such as video, audio, or characters,computer programs, and the like in the CD-ROMs as signals, anddistributes them for sale. Users utilize them by reproducing theirrecorded contents therefrom. Since the WORM disc with a WORM capabilityand without capabilities of erasing and altering written data, and therewritable disc with capabilities of erasing and altering written data,can be used to record data therein and can be accessed randomly byusers, and are relatively high-speed and large-capacity recording media,they are suitable for use in recording video data or audio data, orsuitable for a storage in a computer system.

In the optical disc, as in the case of a magnetic disc recording mediumsuch as a floppy disc or a hard disc, the recording surface on the dischas concentric circular tracks and linear areas in the radial directionthereof, i.e., sectors, which are managed as unit areas, and addressinformation relating to addresses is recorded in specific recordingpositions indicated by the addresses.

An optical disc recording and reproducing apparatus according to theprior art which records data in the optical disc and reproduces datatherefrom, uses an optical head which converges the laser beams to therecording surface thereby reading a signal recorded therein. To readrecorded contents including address information, it is required that theoptical head be moved to an appropriate position on the recordingsurface with high precision. For this purpose, feed back control isperformed, including tracking control for positioning the head in adesired position of the disc or control of disc rotation forrecording/reproduction, as in the case of the magnetic disc medium.

In addition to these control, the apparatus which uses the optical discrequires focusing control for appropriately converging the laser beamsto the recording surface, and laser power control for adjustingintensity of the laser beams. Hence, the optical disc reproducing andrecording apparatus according to the prior art obtains a tracking errorsignal or a focus error signal from the reflected beam, and based onthese signals, a servo system performs feedback control of the positionof the optical head or the laser power. Likewise, the servo systemperforms the feedback control to rotation of the disc by the servosystem.

The optical disc is basically used to record a digital signal therein asa recording medium. The signal recorded in the optical disc isreproduced by irradiating “pits” formed on the optical disc with a laserbeam and reading variations in the intensity of the reflected beam ofmicroscopic signals. In this case, because of optical or electricallow-pass frequency characteristics in a reproducing system, even thoughdata has been digitally recorded in the optical disc, reproducedwaveform thereof becomes analog signals having intermediate values.

Accordingly, the optical disc recording and reproducing apparatusaccording to the prior art which performs the control described above,subjects the signal read from the optical disc to binarization, andperforms various types of control processes by using the analogprocessing system and the digital processing system which handles thebinarized digital signal and performs highly precise and high-speedprocessing.

With recent remarkable development of multi media or computers, opticaldisc recording media of higher density and larger capacities have beendeveloped. The higher density recording requires more highly precisecontrol, while a demand for higher-speed processing goes on increasing.Accordingly, there is a need for an optical disc recording andreproducing apparatus which can handle a large-capacity optical discrecording medium that is capable of executing more highly precisecontrol and performing higher-speed processing including control thanthe prior art apparatus.

As the large-capacity optical disc, there has emerged an optical discwhich employs a recording method different from that of a conventionaloptical disc recording medium. While the conventional optical discmedium generally has grooves along tracks, and contains signals recordedin either of convex and concave portions thereof, some optical discscontain signals recorded in both portions. This type of optical discgenerally has address areas in which respective address information isrecorded for recording in the convex and concave portions, and further,the address areas have been utilized as those having both areas ofconvex and concave portions, to increase recording capacities. In thisoptical disc, the address area has no grooves described above, andtherefore, the address area and the other recording area must becontrolled in different manners.

However, the optical disc recording and reproducing apparatus accordingto the prior art, is not capable of performing high-speed and highlyprecise control for the large-capacity recording medium, and hasdifficulty in appropriately changing control of the optical disc whichhas the address area and the other area, the structures of which differfrom each other.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an optical discrecording and reproducing apparatus which is capable of executing highlyprecise control, thereby recording and reproducing data speedily, by theuse of a high-density and large-capacity optical disc as a recordingmedium.

It is another object of the present invention to provide an optical discrecording and reproducing method which is capable of executing highlyprecise control, thereby recording and reproducing data speedily, whenrecording a signal and reproducing a recorded signal by the use of thehigh-density and large-capacity optical disc as the recording medium.

Other objects and advantages of the invention will become apparent fromthe detailed description that follows. The detailed description andspecific embodiments described are provided only for illustration sincevarious additions and modifications within the spirit and scope of theinvention will be apparent to those skill in the art from the detaileddescription.

According to a first aspect of the present invention, an optical discrecording and reproducing apparatus for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises: analog processing means including abinarization unit for subjecting a signal read from the optical disc tobinarization and a servo unit for controlling recording and reproducinga signal in and from the optical disc; synchronous clock generatingmeans for generating a synchronous clock signal which is synchronizedwith the signal read from the optical disc; address detecting means fordetecting address information indicating a physical position on theoptical disc based on the signal read from the optical disc, andoutputting a signal indicating the address information and a signalindicating that the address has been detected when the addressinformation has been detected; a sector counter for holding a sectorcount value of a sector as a recording unit on the optical disc, andupdating the sector count value according to the synchronous clocksignal and the signal output from the address detecting means; and gatesignal generation switching means for generating a gate signal whichcontrols the analog processing means, based on one of the sector countvalue held in the sector counter and information obtained from theanalog processing means, according to the signal indicating that theaddress has been detected, which is output from the address detectingmeans. Thereby, according to the detection of the address, switching isperformed so that the gate signal for controlling the analog processingsystem is based on the sector counter value or based on the informationobtained from the analog processing system.

According to a second aspect of the present invention, in the opticaldisc recording and reproducing apparatus of the first aspect, theinformation from the analog processing means which is obtained by thegate signal generation switching means is an envelope signal indicatingexistence of a signal on the optical disc, which is generated by thebinarization unit. Thereby, according to the detection of the address,switching is performed so that the gate signal for controlling theanalog processing system is based on the sector counter value or basedon the envelope signal.

According to a third aspect of the present invention, an optical discrecording and reproducing apparatus for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises analog processing means including abinarization unit for subjecting a signal read from the optical disc tobinarization and a servo unit for controlling recording and reproducinga signal in and from the optical disc; synchronous clock generatingmeans for generating a synchronous clock signal which is synchronizedwith the signal read from the optical disc; and clock selecting meansfor selecting one of the synchronous clock signal and a clock signalbased on the information obtained from the analog processing means, andoutputting the selected clock signal as a selection clock signal usedfor controlling the analog processing means. Thereby, depending upon thegeneration of the clock signal, switching of the clock signal for use incontrol is performed between the synchronous clock signal and the signalbased on the information obtained from the analog processing system.

According to a fourth aspect of the present invention, in the opticaldisc recording and reproducing apparatus of the third aspect, theinformation from the analog processing means which is obtained by theclock selecting means is a rotation clock signal based on the rotationof the optical disc, which is generated by the servo unit. Thereby,depending upon the generation of the clock signal, switching of theclock signal for use in control is performed between the synchronousclock signal and the rotation clock signal.

According to a fifth aspect of the present invention, the optical discrecording and reproducing apparatus of the third aspect furthercomprises: a sector counter for holding a sector count value of a sectoras a recording unit on the optical disc, and updating the sector countvalue according to the selection clock signal and a signal output fromaddress detecting means; and gate signal generation switching means forgenerating a gate signal which controls the analog processing meansbased on the sector count value held in the sector counter, according toa signal indicating that an address has been detected, which is outputfrom the address detecting means, wherein the gate signal generationswitching means, when the clock selecting means has performed switchingbetween the clock signals, does not generate the gate signal based onthe sector count value until it receives the signal indicating that theaddress has been detected, as an input. Thereby, immediately afterswitching of selection of the clock signal has been performed, the gatesignal for controlling the analog processing system generated based onthe sector counter value is not used.

According to a sixth aspect of the present invention, an optical discrecording and reproducing apparatus for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises analog processing means including abinarization unit for subjecting a signal read from the optical disc tobinarization and a servo unit for controlling recording and reproducinga signal in and from the optical disc; synchronous clock generatingmeans for generating a synchronous clock signal which is synchronizedwith the signal read from the optical disc; address detecting means fordetecting address information indicating a physical position on theoptical disc based on the signal read from the optical disc, andoutputting a signal indicating the address information and a signalindicating that the address has been detected when the addressinformation has been detected; a sector counter for holding a sectorcount value of a sector as a recording unit on the optical disc, andupdating the sector count value according to the synchronous clocksignal and the signal output from the address detecting means; gatesignal generation switching means for generating a gate signal whichcontrols the analog processing means, based on the sector count valueheld in the sector counter according to the signal indicating that theaddress has been detected, which is output from the address detectingmeans; and flag generating means for supervising generation of the gatesignal by the gate signal generation switching means, and updating ofthe sector count value by the sector counter, generating a flagindicating reliability of the output position of the gate signal, andoutputting the flag to the analog processing means.

Thereby, when the gate signal for controlling the analog processingsystem is generated, relationship between the gate signal and updatedsector counter value is checked, and the information about ofreliability of the output position of the gate signal is transmitted tothe analog processing system.

According to a seventh aspect of the present invention, in the opticaldisc recording and reproducing apparatus of the sixth aspect, the analogprocessing means decides whether or not to perform processing inaccordance with the gate signal, from the flag. Thereby, the processingis performed depending upon the reliability of the output position ofthe transmitted gate signal.

According to an eighth aspect of the present invention, an optical discrecording and reproducing apparatus for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises analog processing means for subjecting thesignal read from the optical disc to binarization and controllingrecording and reproducing a signal in and from the optical disc inanalog processing; and gate signal generation switching means forgenerating a gate signal which instructs the analog processing means toperform switching of gain to be used therein, depending upon a readingresult of a signal from the optical disc. Thereby, depending upon thereading result, switching of gain for feedback control is performed.

According to a ninth aspect of the present invention, in the opticaldisc recording and reproducing apparatus of the eighth aspect, theoptical disc has an address area in which address information indicatinga physical position on the optical disc is recorded, the addressinformation being recorded in different states in the address area, andthe gate signal generation switching means instructs the analogprocessing means to perform the switching, according to differencebetween recording states of the address information. Thereby, dependingupon the recording states of the address information, switching of gainfor feedback control is performed.

According to a tenth aspect of the present invention, an optical discrecording and reproducing method for recording and reproducing data inand from an optical disc by the use of the optical disc as a recordingmedium, comprises: an analog processing step including a binarizationprocess for subjecting a signal read from the optical disc tobinarization and a servo control process for controlling recording andreproducing a signal in and from the optical disc; a synchronous clockgenerating step for generating a synchronous clock signal which issynchronized with the signal read from the optical disc; an addressdetecting step for detecting address information indicating a physicalposition on the optical disc based on the signal read from the opticaldisc, and outputting a signal indicating the address information and asignal indicating that the address has been detected when the addressinformation has been detected; a sector counter step for holding asector count value of a sector as a recording unit on the optical disc,and updating the sector count value according to the synchronous clocksignal and the signal output in the address detecting step; and a gatesignal generation switching step for generating a gate signal whichcontrols the analog processing step, based on one of the sector countvalue held in the sector counter step and information obtained in theanalog processing step, according to the signal indicating that theaddress has been detected, which is output in the address detectingstep. Thereby, according to the detection of the address, switching isperformed so that the gate signal for controlling the analog processingsystem are based on the sector counter value or based on the informationobtained from the analog processing system.

According to an eleventh aspect of the present invention, in the opticaldisc recording and reproducing method of the tenth aspect, theinformation from the analog processing step obtained in the gate signalgeneration switching step is an envelope signal indicating existence ofa signal on the optical disc, which is generated by the binarizationprocess. Thereby, according to the detection of the address, switchingis performed so that the gate signal for controlling the analogprocessing system is based on the sector counter value or based on theenvelope signal.

According to a twelfth aspect of the present invention, an optical discrecording and reproducing method for recording and reproducing data inand from an optical disc by the use of the optical disc as a recordingmedium, comprises: an analog processing step including a binarizationprocess for subjecting a signal read from the optical disc tobinarization and a servo control process for controlling recording andreproducing a signal in and from the optical disc; a synchronous clockgenerating step for generating a synchronous clock signal which issynchronized with the signal read from the optical disc; and a clockselecting step for selecting one of the synchronous clock signal and aclock signal based on the information obtained in the analog processingstep, and outputting the selected clock signal as a selection clocksignal used for controlling the analog processing step. Thereby,depending upon the generation of the clock signal, switching of theclock signal for use in control is performed between the synchronousclock signal and the signal based on the information obtained from theanalog processing system.

According to a thirteenth aspect of the present invention, in opticaldisc recording and reproducing method of the twelfth aspect, theinformation from the analog processing step which is obtained in theclock selecting step is a rotation clock signal based on the rotation ofthe optical disc which is generated by the servo control process.Thereby, depending upon the generation of the clock signal, switching ofthe clock signal for use in control is performed between the synchronousclock signal and the rotation clock signal.

According to a fourteenth aspect of the present invention, the opticaldisc recording and reproducing method of the twelfth aspect furthercomprises: a sector counter step for holding a sector count value of asector as a recording unit on the optical disc, and updating the sectorcount value according to the selection clock signal and a signal outputin an address detecting step; and a gate signal generation switchingstep for generating a gate signal which controls the analog processingstep based on the sector count value held in the sector counter step,according to a signal indicating that an address has been detected,which is output in the address detecting step, wherein in the gatesignal generation switching step, when the clock selecting step hasperformed switching between the clock signals, the gate signal is notgenerated based on the sector count value until the signal indicatingthat the address has been detected is input. Thereby, immediately afterswitching of selection of the clock signal has been performed, the gatesignal for controlling the analog processing system generated based onthe sector counter value is not used.

According to a fifteenth aspect of the present invention, an opticaldisc recording and reproducing method for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises: an analog processing step including abinarization process for subjecting a signal read from the optical discto binarization and a servo control process for controlling recordingand reproducing a signal in and from the optical disc; a synchronousclock generating step for generating a synchronous clock signal which issynchronized with the signal read from the optical disc; an addressdetecting step for detecting address information indicating a physicalposition on the optical disc based on the signal read from the opticaldisc, and outputting a signal indicating the address information and asignal indicating that the address has been detected when the addressinformation has been detected; a sector counter step for holding asector count value of a sector as a recording unit on the optical disc,and updating the sector count value according to the synchronous clocksignal and the signal output in the address detecting step; a gatesignal generation switching step for generating a gate signal whichcontrol the analog processing step, based on the sector count value heldin the sector counter step, according to the signal indicating that theaddress has been detected, which is output in the address detectingstep; and a flag generating step for supervising generation of the gatesignal in the gate signal generation switching step, and updating of asector count value in the sector counter step, generating a flagindicating reliability of the output position of the gate signal, andoutputting the flag to the analog processing step. Thereby, when thegate signal for controlling the analog processing system is generated,relationship between the gate signal and the updated sector countervalue is checked, and the information about of reliability of the outputposition of the gate signal is transmitted to the analog processingsystem.

According to a sixteenth aspect of the present invention, in the opticaldisc recording and reproducing method of the fifteenth aspect, in theanalog processing step, it is decided whether or not to performprocessing in accordance with the gate signal, from the flag. Thereby,the processing is performed depending upon the reliability of the outputposition of the transmitted gate signal.

According to a seventeenth aspect of the present invention, an opticaldisc recording and reproducing method for recording and reproducing datain and from an optical disc by the use of the optical disc as arecording medium, comprises: an analog processing step for subjectingthe signal read from the optical disc to binarization and controllingrecording and reproducing a signal in and from the optical disc inanalog processing; and a gate signal generation switching step forgenerating a gate signal which instructs the analog processing step toperform switching of gain to be used therein, depending upon a readingresult of a signal from the optical disc. Thereby, depending upon therecording states of the address information, switching of gain forfeedback control is performed.

According to an eighteenth aspect of the present invention, in theoptical disc recording and reproducing method of the seventeenth aspect,the optical disc has an address area in which address informationindicating a physical position on the optical disc is recorded, theaddress information being recorded in different states in the addressarea, and the gate signal generation switching step instructs the analogprocessing step to perform the switching, according to differencebetween recording states of the address information. Thereby, dependingupon the recording states of the address information, switching of gainfor feedback control is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an optical disc recording andreproducing apparatus according to a first and second embodiment of thepresent invention.

FIGS. 2(a)–(d) are diagrams for explaining an envelope signal for use bythe optical disc recording and reproducing apparatus according to thefirst embodiment.

FIGS. 3(a)–(c) are diagrams for explaining a flag for use by the opticaldisc recording and reproducing apparatus of the first embodiment.

FIGS. 4(a)–(e) are diagrams for explaining control process by the use ofan address gate signal performed by the optical disc recording andreproducing apparatus of the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1

In an optical disc recording and reproducing apparatus according to afirst embodiment of the present invention, a control signal is generatedbased on a signal obtained from an analog processing system and a signalobtained from a digital processing system, and control is performed bythe use of the control signal.

FIG. 1 is a block diagram showing a construction of the optical discrecording and reproducing apparatus of the first embodiment. Adescription will be given of the construction of the apparatus. Turningto FIG. 1, the optical disc recording and reproducing apparatuscomprises an optical disc drive 100, an analog processing system 120, adata demodulating circuit 105, an address detecting circuit 106, a gatesignal generation switching circuit 107, a flag generating circuit 108,a sector counter 109, and a clock selecting circuit 110. The analogprocessing system 120 comprises a data binarization block 101, a datasynchronous clock generation PLL (phase-locked loop) 102, a servo 103,and a laser control 104.

The optical disc drive 100 is provided with a motor which rotates anoptical disc as a recording medium, and an optical head which records(write) data in the optical disc and reproduces (reads) data therefromby the use of laser beams, under the control of the analog processingsystem 120.

As in the case of the prior art apparatus, the signal recorded in theoptical disc is input to the analog processing system 120, and issubjected to binarization, resulting in a binarized digital signal. Thebinarization block 101 is used for performing binarization to a signalS131 read from the optical disc which is output from the optical discdrive 100, to generate a binarized signal S132 which takes a value “0”or “1”. The data synchronous clock generation PLL 102 is used forperforming PLL process by the use of the read signal S131 to generate asynchronous clock signal S137 which is synchronized with the inputsignal S131.

The servo 103 is Used for outputting a control signal S142 to theoptical disc drive 100 in accordance with a gate signal S136 b, therebyperforming focusing control which controls a focal point, trackingcontrol which controls positioning the optical head in a desiredrecording position on the optical disc, and control of rotation of theoptical disc. The laser control 104 is used for outputting a controlsignal S141 to the optical disc drive 100 in accordance with a gatesignal S136 c, thereby controlling intensity of laser light used inrecording and reproducing data in and from the optical disc.

The data demodulating circuit 105 is used for demodulating modulateddata to generate data before modulation. This demodulation is performedto the signal S132 based on modulated data in a way adapted to themodulation, in order to reduce DC (direct current) components, whenwriting to the optical disc is performed. The resulting demodulatedsignal S133 is based on the data recorded in either of the optical discand address information thereon.

The address detecting circuit 106 is used for receiving the demodulatedsignal S133 based on the address information as an input and detectingaddress information of a sector on the optical disc which is to be read.

The gate signal generation switching circuit 107 is used for generatinga gate signal by which the analog processing system 120 is controlled,and outputting the gate signal to the data binarization 101, the servo103, and the laser control 104 in the analog processing system 120. Thegate signal serves as a control signal. One of the roles of the gatesignal is to instruct the analog processing system 120 to performswitching between modes, so as to perform appropriate processing for therecording areas. On the optical disc used in the recording andreproducing apparatus of the first embodiment, there are provided asector as a data recording area in which data is recorded, and a sectoras an address area in which address information indicating addresses isrecorded. The address area is formed when creating the optical disc, andsignificantly differ from the data recording area in a reflectance, arecording format (storage state of a signal indicating “0” or “1”), orthe existence/non-existence of guide grooves. For this reason, it isrequired that the processing to the address area performed by the analogprocessing system 120 differ from the processing to the data recordingarea performed by the same. In the optical disc recording andreproducing apparatus of the first embodiment, the gate signal is usedto control switching between these processing performed by the analogprocessing system 120. In accordance with the gate signal, the analogprocessing system 120 performs switching between an address areaprocessing mode and a data recording area processing mode. The gatesignal is also used to transmit the address information which indicatesthe reading position on the optical disc, to the analog processingsystem 120.

The flag generating circuit 108 is used for generating a flag indicatingreliability of the output position of the gate signal as the controlsignal to the analog processing system 120. The sector counter 109 isused for holding a sector count value indicating a physical position onthe optical disc, and updating the sector count value according to aselection clock signal input from the clock selecting circuit 110 and anaddress detection signal input from the address detecting circuit 106.

The clock selecting circuit 110 is used for selecting one of thesynchronous signal generated by the data synchronous clock generationPLL 102 and a fixed clock generated by the servo 103, and outputting theselected clock signal to the sector counter 110.

Hereinafter, a description will be given of operation of reproducingdata from the optical disc performed by the optical disc recording andreproducing apparatus of the first embodiment so constructed as “A.Basic Operation”, “B. Control by the Use of Envelope Signal”, “C. ClockSwitching”, “D. Control by Use of Flag”. The description will be inlarge part given of control in the analog processing system 120.

A. Basic Operation

When data reproduction from the optical disc starts, the optical disc isrotated and the tracking control is executed under the control of theservo 103. The servo 103 outputs a tracking OK signal S140 to the gatesignal generation switching circuit 107. Receiving the tracking OKsignal S140, the gate signal generation switching circuit 107 generatesgate signals S36 a–S136 c in accordance with which processing isperformed in an address processing mode, and outputs these signals tothe data binarization block 101, the servo 103, and the laser control104 in the analog processing system 120. The analog processing system120 enters the address area processing mode. Since no guide grooves areprovided in the address area, the servo 103 holds tracking. The lasercontrol 104 performs control so that laser power for the address area isappropriately used in the optical disc drive 100.

The optical disc drive 100 reads the signal as the address informationrecorded in the optical disc. The read signal S131 is input to the databinarization block 101 and the data synchronous clock generation PLL 102in the analog processing system 120. The data binarization block 101subjects the signal S131 to binarization, and outputs the resultingbinarized signal S132 to the data demodulating circuit 105. The datademodulating circuit 105 demodulates the binarized signal S132, andoutputs the resulting demodulated signal S133 to the address detectingcircuit 106. The address detecting circuit 106 detects an address of theinput signal S133, and outputs an address signal S134 indicating theaddress has been detected and address information when the addressinformation has been detected, to the gate signal generation switchingcircuit 107 and the sector counter 109. In the optical disc for use bythe first embodiment, according to a general format, the addressinformation contains specific mark data termed an “address mark”. Theaddress detecting circuit 106 detects the address information by usingthe address mark in the demodulated signal S133 as an indication.Following the address information, an error detection code used fordetection of correctness/incorrectness of the address information ispresent. According to the error detection code, the address detectingcircuit 106 detects an error.

Receiving the read signal S131, the data synchronous clock generationPLL 102 performs PLL process, to generate the synchronous clock signalS137 which is synchronized with the input signal S131. The datasynchronous clock generation PLL 102 generates a PLL synchronization OKsignal S151 indicating that the PLL process has been performed, andoutputs the OK signal S151 and the synchronous clock signal S137 to theclock selecting circuit 110. The clock selecting circuit 110 selects thesynchronous clock signal S137 when the PLL synchronization OK signalS151 indicating synchronization is input thereto, and outputs thesynchronous clock signal S137 to the sector counter 109 as the selectedclock signal S153.

Receiving the selected clock signal S153 and the address signal S134 asinputs, a correct sector count value is preset in the sector counter109. The sector counter 109 outputs a counter synchronization timingsignal S135 based on the sector counter value preset correctly to thegate signal generation switching circuit 107. Thereafter, the sectorcounter 109 updates a sector count value according to the selected clocksignal S153, and outputs the counter synchronization timing signal S135based on the updated sector count value to the gate signal generatingcircuit 107. Therefore, when reading for continuous areas is performedafter the sector count value has been correctly preset, updated sectorcount values transmit correct address position information.

Receiving the signal S134 from the address detection circuit 106 and thecounter synchronization timing signal S135 from the sector counter 109as inputs, the gate signal generation switching circuit 107 generates asignal designating the data recording area mode, and outputs the gatesignals S136 a–S136 c including the signal and a signal indicatingaddress information based on the signal S135, to the analog processingsystem 120. The analog processing system 120 enters the data recordingarea mode. The servo 103 releases a “Hold” state of tracking, and thenperforms feedback control for the data recording area. The laser control104 performs control so that the laser power for the data recording areais appropriately used. In this manner, the address position informationof the data which is to be read is obtained, and data can be reproducedappropriately.

The signal S131 based on the data which has been read from the datarecording area is also subjected to binarization by the databinarization block 101, and demodulated by the data demodulating circuit105. The resulting signal is output as the output of the optical discrecording and reproducing apparatus. The address signal S134 containingthe address information which has been detected by the address detectingcircuit 106 can also be used externally as the output of the apparatus.

On the other hand, when the address detecting circuit 106 has notdetected the address, the sector counter 109 updates the sector countvalue according to the synchronous clock signal, and outputs the countersynchronization timing signal S135 based on the updated sector countervalue to the gate signal generation switching circuit 107. The switchingcircuit 107 generates the gate signals S136 a–S136 c indicating addressposition information based on the signal S135 and outputs these signalsto the analog processing system 120. The analog processing system 120performs reading from the optical disc while maintaining the addressarea mode. Updating the sector count value and reading in accordancewith the gate signal based on the updated sector count value arerepeated until the address is detected.

B. Control by Use of Envelope Signal

In “A. Basic Operation”, desired address information is obtainedspeedily. However, this sometimes becomes impossible. For instance,immediately after reading from the optical disc has started, or whenreading cannot be performed smoothly due to the flaw of the optical discsurface, the address information is not obtained speedily.

In such cases, assuming now that operation shown in “A. Basic Operation”is performed until the address detecting circuit 106 has detected theaddress, the operation is carried out under poor feedback control in thestate where the analog processing system 120 is in the address area modeand the servo 103 holds tracking, whereby some time elapses due to delaycaused by the poor control until the address is detected. Moreover, insome cases, addresses cannot be detected continuously, and the sectorcount value held in the sector counter 109 becomes significantlydifferent from the correct address value. In such cases, since the gatesignal based on the sector counter value which is significantlydifferent from the correct value, is output, poor tracking controloccurs in the analog processing system 120. If the system 120 returns tothe initial state, and retries the initial tracking operation again,then more and more time becomes necessary.

In the optical disc recording and reproducing apparatus according to thefirst embodiment, the analog processing system 120 outputs the envelopesignal indicating the position of a signal, and the gate signalgeneration switching circuit 107 performs switching between the gatesignal based on the sector count value and the gate signal based on theenvelope signal, to be output, depending upon the reading result theaddress information.

The data binarization block 101 generates an envelope signal Sl60indicates that pits are present on the optical disc, and outputs theenvelope signal Sl60 to the gate signal generation switching circuit107. The envelope signal S151 contains a pit envelope signal indicatingthat the pits are present in the address area or the data recording areaon the optical disc, and an address envelope signal indicating that thepits are present in the address area. As mentioned previously, sincethere is difference of reflectances between the address area and thedata recording area, the data binarization block 101 generates the pitenvelope signal and the address envelope signal based on the difference.

FIGS. 2 is a conceptual diagram showing storage state of a signal on theoptical disc. In the figure, a) shows a sector format showing astructure of the recording area on the optical disc. As described above,the address area and the data recording area are provided. In the samefigure, b) shows the state of the pits, c) shows the pit envelopesignal, and d) shows the address envelope signal. As can be seen fromthe figure, the pit envelope signal is output at H (high) level when thepits are present in either of the address area and the data recordingarea, and the address envelope signal is output at H(high) level onlywhen the pits are present in the address area.

The gate signal generation switching circuit 107 of the first embodimentincludes a state transition machine, for supervising detection of anaddress, and performing switching between the gate signal based on thesector count value and the gate signal based on the envelope signal,depending upon the detection. When a state transition condition is set,for example, by receiving the tracking OK signal S140 as an input, thecircuit 107 outputs the signal for instructing the analog processingsystem 120 to perform processing in the address area mode, andthereafter, if the address has not been detected in a predeterminednumber of sectors, then the circuit 107 carries out switching, therebyperforming control by the use of the gate signal based on the envelopesignal S160.

When the analog processing system 120 is reading data from the datarecording area while remaining in the address area mode, in theoperation shown in “A. Basic Operation”, after the address has not beendetected in the predetermined number of sectors, the gate signalgeneration switching circuit 107 performs switching so that the gatesignal is generated based on the envelope signal S160 as describedabove. In this case, as for the envelope signal S160, the level of thepit envelope signal in FIG. 2( c) is H, while the level of the addressenvelope signal in FiG. 2( d) is L(low). Sine the envelope signal Sl60is generated by the analog processing system 120, and therefore containsnoise and the like, the gate signal generation switching circuit 107eliminates the noise contained therein, and then generates the gatesignals S136 a–136 c based on this, and outputs these signals to theanalog processing system 120, in accordance with which, the system 120enters the data recording area mode. The servo 103 releases the“TRACKING HOLD”, and executes the feedback control smoothly. Thereby,the analog processing system 120 performs appropriate processing, andadverse effects on the control system due to delay of address detectionis avoided.

Rather than control by the use of the gate signal based on the envelopesignal generated by the analog processing system, it is preferable toperform control by the use of the gate signal based on the sector countvalue generated by the digital processing system, because the control iscarried out with high precision. It is therefore desirable for the gatesignal generation switching circuit 107 to set the state transitioncondition in the state transition machine so that the control in thedigital system is performed with priority.

In the first embodiment, the envelope signal is output from the analogprocessing system 120 to the gate signal generation switching circuit107, and the analog processing system 120 is controlled by the digitalgate signal. Although it is possible that the data binarization block101 generates the envelope signal, which is used in the analogprocessing system 120 to perform analog control, control in the digitalsystem is more preferable in the whole system as described above. Hence,to switch from the analog control to the digital control with the aboveconstruction, the signal indicating that the address has been detectedis also input to the analog processing system 120, to perform switchingtherein, causing the control system to be more complicated. As asolution to this, in the first embodiment, the envelope signal S160 isinput to the gate signal generation switching circuit 107, to manage thecontrol signal therein unifyingly.

C. Clock Switching

While the signal is read from the optical disc smoothly and the datasynchronous clock generation PLL 102 smoothly generates the synchronousclock signal S137 in the “A. Basic Operation”, the signalto-be-processed by the PLL 102 runs out if the optical disc drive 100reads data from areas in which no data is recorded. In this state, thePLL 102 holds PLL process, and outputs an oscillation frequency as afixed output obtained by system setting.

In this “HOLD” state, if some fluctuations in rotation of the discoccur, the clock signal to be in synchronization is sometimes lacking insynchronization due to the fluctuations. In this case, the sectorcounter 109 updates the sector count value by the use of the clocksignal lacking in synchronization, and correspondingly precision ofcontrol based on the sector count value is degraded, which makes itimpossible to detect the address or reproduce recorded datasuccessfully.

In the first embodiment, the servo 103 generates a rotation clock signalS138, i.e., a clock signal based on rotation of the optical disc. Theclock selecting circuit 110 selects one of the synchronous clock signalS137 and the rotation clock signal S138, and outputs the selected signalto the sector counter 109. The rotation clock signal S138 is used toavoid the state with low controllability when the reliability of thesynchronous clock signal S137 is low.

The servo 103 controls rotation of the optical disc drive 100 asdescribed above, generates the rotation clock signal S138 based on therotation of the optical disc, and outputs the rotation clock signal S138to the clock selecting circuit 110. In addition, the servo 103supervises rotational stability. When rotation is stable, the servo 103generates a rotation OK signal S152 indicating this, and outputs the OKsignal S152 and the rotation clock signal S138 to the clock selectingcircuit 110.

The data synchronous clock generating circuit PLL 102 receives the readsignal S131 as an input, and when the PLL 102 executes PLL control andgenerates the synchronous clock signal S137, the PLL 102 generates a PLLsynchronization OK signal S151 indicating synchronization, and outputsthe OK signal S151 and the synchronous clock signal S137 to the clockselecting circuit 110. On the other hand, when the PLL 102 does notgenerate the signal synchronized with the read signal S131, which ispositioned in the area where no data is recorded as described above, itoutputs the clock signal S137 based on the fixed frequency to the clockselecting circuit 110 instead of outputting the PLL synchronization OKsignal S151.

When the PLL synchronization OK signal S151 indicates synchronization inthe PLL102, the clock selecting circuit 110 selects the synchronousclock signal S137, and outputs the synchronous clock signal S137 to thesector counter 109 as the selection clock signal S153. Use of thesynchronous clock signal S137 provides higher precision in control thanuse of the rotation clock signal S138 generated by the analog processingsystem 120. For this reason, the clock selecting circuit 110 selects thesynchronous clock signal S137 regardless of the state of the rotation OKsignal S152, when the PLL synchronization OK signal S151 indicatessynchronization.

When the information indicating synchronization in the PLL 102 is notobtained from the PLL synchronization OK signal S151, the clockselecting circuit 110 checks whether or not the rotation OK signal S152from the servo 103 indicates that rotation is stable. When the signalS152 indicates that rotation is stable, the clock selecting circuit 110selects the rotation clock signal S138, and outputs the clock signalS138 to the sector counter 109 as the selection clock signal S153.

When it is decided that neither the PLL synchronization nor rotationalstability is obtained, from the PLL synchronization OK signal S151 andthe rotation OK signal S152, respectively, the clock selecting circuit110 selects the synchronous clock signal S137. The synchronous clocksignal S137 which is output on a fixed basis is used rather than therotation clock signal S138, for the time period from when the opticaldisc starts rotating until it rotates with stability, or the case wherefluctuations occur in the rotation of the optical disc for some reason.

In this manner, the clock selecting circuits performs switching betweenthe clock signals S137 and S138 according to the PLL synchronization OKsignal S151 and the rotation OK signal S152. However, there is apossibility that the sector count value held in the sector counter 109is different from the correct value immediately after this switching. Asa solution to this, the sector counter 109 of the first embodimentdetects switching of the clock signal, and outputs a switching detectionsignal contained in the counter synchronization timing signal S135 andindicating that the switching has been performed, to the gate signalgeneration switching circuit 107.

Receiving the switching detection signal as an input, the gate signalgeneration switching circuit 107 does not use the countersynchronization timing signal S135 containing the switching detectionsignal, and does not generate the gate signal based on the sectorcounter value different from the correct value, until it confirms thatthe signal S134 input from the address detecting circuit 106 indicatesthat the address has been detected. Receiving the signal indicating thatthe address has been detected, the gate signal generation switchingcircuit 107 uses the counter synchronization timing signal S135 togenerate the gate signal based on the sector count value, since thesector count value is preset in the sector counter 109 as the correctvalue.

D. Control by the Use of Flag

As already described in the “A. Basic Operation”, after the correctvalue is preset in the sector counter 109, control is performed smoothlyby the use of the gate signal based on the sector count value, andthereafter, for data recorded continuously, the sector count value isupdated according to the synchronous clock signal, to correctly obtainan address to be subsequently read. On the other hand, when data is notrecorded continuously or another read out is performed, after theaddress is detected in operation shown in A.–C., a correction is made bypresetting the correct value in the sector counter 109 again.

After this correction, an appropriate gate signal is output, and therebycontrol is carried out smoothly. On the other hand, since the gatesignal S136 output before the correction has low reliability, if theanalog processing system 120 executes control by the use of the gatesignal S136, precision in control is reduced.

In the first embodiment, the flag generating circuit 108 supervises thestatus of the correction, to check whether or not the correction hasbeen made. The circuit 108 generates the flag indicating whether to beaccording to the gate signal S136 or not, and outputs the flag to theanalog processing system 120, thereby improving precision in processingperformed by the analog processing system 120.

The flag generating circuit 108 receives a gate generation signal S136 daccording to the gate signals S136 a–136 c output to the analogprocessing system 120 from the gate signal generation switching circuit107. The flag generating circuit 108 also receives a signal S139containing a signal indicating that the sector count value has beenupdated, and a signal indicating that the correction has been made, fromthe sector counter 109.

FIG. 3 is a diagram for explaining generation of the flag in the flaggenerating circuit 108. In the figure, like the a) in FIG. 2, a) shows asector format of the optical disc, b) shows the output state of the gatesignal in the gate signal generation switching circuit 107, and c) showsgeneration of the flag in the flag generating circuit 108.

As can be seen from b), when the gate signal generation switchingcircuit 107 outputs the gate signal S136, the flag generating circuit108 to which the signal S136 d has been input, starts countingoperation. This counting operation is carried out according to thesignal S139 input from the sector counter 109 when it indicates that thesector count value has been updated, and is continued until the signalS139 indicates that the correction has been made, or the count value hasreached a predetermined upper limit.

In the case of b), the correction indicated by “Cor” is made at the endof the address area. The flag generating circuit 108 carries out thecounting operation in the areas between “Cl_Cnt”. The flag generatingcircuit 108 decides whether or not the resulting count value is within arange indicated by a predetermined threshold. When it is within therange, the flag generating circuit 108 generates the flag shown in c),and outputs the flag S161 to the analog processing system 120.

When the flag S161 is input to the analog processing system 120 during aperiod after the gate signals S136 a–136 c have been input, it isdecided that the sector counter 109 has made the correction immediatelyafter the gate signals S136 a–S136 c is output, and accordingly, theanalog processing system 120 does not carry out control according to thegate signals S136 a–136 c with low reliability and maintains the controlstatus before the gate signals S136 a–S136 c are input, whereas itperforms control by the use of the following input gate signals.Thereafter, the gate signal generation switching circuit 107 outputs thegate signals S136 a–S136 c based on the correct counter value which hasbeen corrected which is output from the sector counter 109, and by theuse of the gate signals, the analog processing system 120 is capable ofperforming preferable control.

Thus, in accordance with the first embodiment, the optical discrecording and reproducing apparatus comprises the optical disc drive100, the analog processing system 120, the data demodulating circuit105, the address detecting circuit 106, the gate signal generationswitching circuit 107, the flag generating circuit 108, the sectorcounter 109, and the clock selecting circuit 110, wherein the signalobtained by the analog system and the signal obtained by the digitalsystem are used to perform control to the analog processing system withhigh precision depending upon the status of signal processing, therebyallowing speedy data processing.

In addition, in accordance with the optical disc recording andreproducing apparatus of the first embodiment, the sector counter 109holds and updates the sector count value, the data binarization block101 in the analog processing system 120 outputs the envelope signal S160depending upon the status in which the signal is recorded on the opticaldisc, and the gate signal generation switching circuit 107 generates thegate signals S136 a–S136 c based on the sector count value held in thesector counter 109 or the envelope signal. Therefore, even if some delayoccurs in reading the address information because control is beingperformed by the gate signals based on the sector count value, it ispossible to avoid adverse effects caused by such delay on the analogprocessing system 120.

Yet in addition, in accordance with the optical disc recording andreproducing apparatus of the first embodiment, in the analog processingsystem 120, the data synchronous clock generation PLL 102 outputs thesynchronous clock signal S137 synchronized with the signal S131 readfrom the optical disc, the servo 103 outputs the rotation clock signalS138 based on the rotation of the optical disc, the clock selectingcircuit 110 to which these clock signals are input selects either of thesynchronous signal S137 and the rotation clock signal S138 dependingupon the status in which the clock signal is generated, and the sectorcounter 109 uses the selected clock signal. Therefore, even if thesynchronous clock signal is not generated appropriately, it is possibleto avoid reduction of precision in control based on the sector countvalue updated according to the clock signal.

Further, in accordance with the optical disc recording and reproducingapparatus of the first embodiment, the flag generating circuit 108generates the flag Sl6l indicating closeness relationship between thegate signals S136 a–S136 c output to the analog processing system 120and the correction of the sector count value in the sector counter 109,and outputs the flag S161 to the analog processing system 120, whichdoes not perform processing according to the gate signals with lowreliability which are output before the sector count value is corrected,to suppress reduction of precision in control.

Still further, while in the first embodiment, the description has beengiven of the control operation for reproducing data recorded in theoptical disc, recording data in the optical disc is controlled withprecision in the same manner.

Embodiment 2

An optical disc recording and reproducing apparatus according a secondembodiment of the present invention uses an optical disc having anaddress area in a recording format which is adapted to a large capacityand a high density, as a recording medium.

The optical disc recording and reproducing apparatus of the secondembodiment has a construction identical to that of the first embodiment,and therefore a description will be given with reference to FIG. 1.

In the optical disc recording medium, data is recorded in convexportions and concave portions of grooves along the tracks in the opticaldisc recording surface, to realize high-density and large-capacityrecording. In addition, data is recorded in the address area in thehigh-density recording format, to realize effective use of a storagearea. The optical disc of the second embodiment has also address anddata recording areas formed when creating the optical disc, as in thecase of the optical disc for use by the first embodiment. The groovesare formed only in the data recording area, and in the convex portionsand concave portions thereof, data is recorded. Address recordingpositions arranged in the address area are shifted from each other sothat the address information in the data recording area of the convexportions and the address information in the data recording area of theconcave portions share the address area, thereby recording dataefficiently.

FIG. 4 is a diagram for explaining a recording method of the opticaldisc, generation of a gate signal according to a second embodiment, andprocessing in an analog processing system. In the figure, a) shows asector format of the optical disc as in the FIGS. 2–3, b) and d) showsthe states in which address part gate signals of gate signals outputfrom the gate signal generation switching circuit 107, which instructsthe analog processing system 120 to perform processing in the addressarea mode, are output, and c) and e) show waveform of signal processingperformed to the address part gate signals in b) and d) by analogprocessing system 120.

As shown in a), address information, i.e., addresses 1 and 2, to berecorded are shifted from each other in the address area on the opticaldisc for use by the second embodiment. In the optical disc recording andreproducing apparatus of the second embodiment, when the addressinformation shifted from each other(addresses 1 and 2) is sequentiallyread in, the shifted recording position of the address information isdetected. Upon the detection, as shown in b), the level of the addresspart gate information indicating the address area switches from “H” to“L”, and maintains “L” for a short period.

The analog processing system 120 in FIG. 1, starts performing high gaincontrol according to the rising of the address part gate signals in 4 b)and 4 d), thereby realizing speedy follow-up in the PLL control, andwhen some leading-in is completed, the control is switched from thehigh-gain control to low-gain control for the PLL. As shown in d), whenthe address part gate signal B without this switching for a short periodis output, the high-gain control is started according to the rising ofthe address part gate signal B when performing reading out the address1, and thereafter, the control is switched from the high-gain control tothe low-gain control, and the address 2 is read out. At this time, thelow-gain control is performed, and therefore speedy control cannot beperformed as can be observed from the analog processing waveform B ine).

On the other hand, the optical disc apparatus of the second embodiment,as shown in b), upon the detection of the shift of the address recordingposition, the level of the address part gate signal switches from “H” to“L”, and maintains “L” for a short period. Hence, according to thesecond rising of the gate signal A (H level), the analog processingsystem 120 starts performing the high-gain control. Thereby, as can beobserved from the analog processing waveform A shown in c), speedycontrol can be carried out in contrast with the case in e).

Thus, in accordance with the optical disc recording and reproducingapparatus of the second embodiment having the construction identical tothat of the first embodiment, the optical disc having an address area ofthe high-density recording format is used as the recording medium, theshift of the recording position of the address information in theaddress area is detected, the level of the address part gate signalcontained in the gate signals S136 a–S136 c output from the gate signalgeneration switching circuit 107 is made to switch from “H” to “L” for ashort period, thereby realizing speedy follow-up of signal processing inthe analog processing system 120. As a result, precision in control isimproved and speedy data processing is realized.

As for the analog processing system 120, the data demodulating circuit105, the address detecting circuit 106, the gate signal generationswitching circuit 107, the flag generating circuit 108, the sectorcounter 109, and the clock selecting circuit 110 shown in the first orsecond embodiment, the part or the all of which may constitute the sameintegrated circuit. Besides, as for the optical disc recording andreproducing apparatus of the first or second embodiment, a part or allof the digital processing system including the gate signal generationswitching circuit 107 and the sector counter 109,and the analogprocessing system 120 may constitute the same integrated circuit, and achip, namely, one or a plurality of integrated circuits, is preferablyused in the optical disc drive or the system including necessaryinput/output devices and the like.

1. An optical disc reproducing method, comprising: analog processing andbinarizing a signal read from an optical disc; and switching among atleast two modes for generating a gate signal, the generated gate signalfor instructing the analog processing to perform switching of gain to beused therein, said switching depending upon the signal read from anoptical disc.
 2. The optical disc reproducing method of claim 1, whereingenerating a gate signal causes the analog processing to switch betweenvalues of gain, according to a difference between recording states ofthe address information, the address information being recorded indifferent states in an address area of an optical disc.
 3. The opticaldisc reproducing method of claim 1, wherein one of the two modes forgenerating a gate signal is a mode in which the gate signal is generatedbased on an analog signal.
 4. The optical disc reproducing method ofclaim 3, wherein immediately after reading from an optical disc hasstarted, the mode for generating the gate signal is the mode based on ananalog signal.
 5. The optical disc reproducing method of claim 1,wherein said two modes for generating a gate signal are a mode in whichthe gate signal is generated based on a digital signal, and a mode inwhich the gate signal is generated based on an analog signal.
 6. Theoptical disc reproducing method of claim 5, wherein immediately afterreading from the optical disc has started, the mode for generating thegate signal is the mode based on the analog signal.
 7. The optical discreproducing method of claim 3, wherein said analog signal is an envelopesignal.
 8. The optical disc reproducing method of claim 5, wherein saiddigital signal is a counter value.
 9. An optical disc reproducingmethod, comprising: analog processing and binarizing a signal read froman optical disc; and switching among at least two modes for generating agate signal, the generated gate signal for instructing the analogprocessing to perform switching between an address area and a datarecording area.
 10. The optical disc reproducing method of claim 9,wherein one of the two modes for generating a gate signal is a mode inwhich the gate signal is generated based on an analog signal.
 11. Theoptical disc reproducing method of claim 10, wherein immediately afterreading from an optical disc has started, the mode for generated thegate signal is the mode based on an analog signal.
 12. The optical discreproducing method of claim 9, wherein said two modes for generating agate signal are a mode in which the gate signal is generated based on adigital signal, and a mode in which the gate signal is generated basedon an analog signal.
 13. The optical disc reproducing method of claim12, wherein immediately after reading from an optical disc has started,the mode for generating the gate signal is the mode based on the analogsignal.
 14. The optical disc reproducing method of claim 10, whereinsaid analog signal is an envelope signal.
 15. The optical discreproducing method of claim 12, wherein said digital signal is a countervalue.